From: Dave Young <dyoung@redhat.com>
To: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: vgoyal@redhat.com, bhe@redhat.com, mpe@ellerman.id.au,
bauerman@linux.vnet.ibm.com, prudo@linux.vnet.ibm.com,
kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Subject: Re: [PATCH 5/7] x86: kexec_file: lift CRASH_MAX_RANGES limit on crash_mem buffer
Date: Fri, 2 Mar 2018 13:31:53 +0800 [thread overview]
Message-ID: <20180302053153.GC2952@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <20180227044814.24808-6-takahiro.akashi@linaro.org>
On 02/27/18 at 01:48pm, AKASHI Takahiro wrote:
> While CRASH_MAX_RANGES (== 16) seems to be good enough, fixed-number
> array is not a good idea in general.
>
> In this patch, size of crash_mem buffer is calculated as before and
> the buffer is now dynamically allocated. This change also allows removing
> crash_elf_data structure.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Vivek Goyal <vgoyal@redhat.com>
> Cc: Baoquan He <bhe@redhat.com>
> ---
> arch/x86/kernel/crash.c | 80 ++++++++++++++++++-------------------------------
> 1 file changed, 29 insertions(+), 51 deletions(-)
>
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index 913fd8021f8a..bfc37ad20d4a 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -41,32 +41,14 @@
> /* Alignment required for elf header segment */
> #define ELF_CORE_HEADER_ALIGN 4096
>
> -/* This primarily represents number of split ranges due to exclusion */
> -#define CRASH_MAX_RANGES 16
> -
> struct crash_mem_range {
> u64 start, end;
> };
>
> struct crash_mem {
> - unsigned int nr_ranges;
> - struct crash_mem_range ranges[CRASH_MAX_RANGES];
> -};
> -
> -/* Misc data about ram ranges needed to prepare elf headers */
> -struct crash_elf_data {
> - struct kimage *image;
> - /*
> - * Total number of ram ranges we have after various adjustments for
> - * crash reserved region, etc.
> - */
> unsigned int max_nr_ranges;
> -
> - /* Pointer to elf header */
> - void *ehdr;
> - /* Pointer to next phdr */
> - void *bufp;
> - struct crash_mem mem;
> + unsigned int nr_ranges;
> + struct crash_mem_range ranges[0];
> };
>
> /* Used while preparing memory map entries for second kernel */
> @@ -217,26 +199,29 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
> return 0;
> }
>
> -
> /* Gather all the required information to prepare elf headers for ram regions */
> -static void fill_up_crash_elf_data(struct crash_elf_data *ced,
> - struct kimage *image)
> +static struct crash_mem *fill_up_crash_elf_data(void)
> {
> unsigned int nr_ranges = 0;
> -
> - ced->image = image;
> + struct crash_mem *cmem;
>
> walk_system_ram_res(0, -1, &nr_ranges,
> get_nr_ram_ranges_callback);
I know it is probably not possible fail here, but for safe we can check
if nr_ranges == 0
>
> - ced->max_nr_ranges = nr_ranges;
> + /*
> + * Exclusion of crash region and/or crashk_low_res may cause
> + * another range split. So add extra two slots here.
> + */
> + nr_ranges += 2;
> + cmem = vmalloc(sizeof(struct crash_mem) +
> + sizeof(struct crash_mem_range) * nr_ranges);
> + if (!cmem)
> + return NULL;
vzalloc will be better.
>
> - /* Exclusion of crash region could split memory ranges */
> - ced->max_nr_ranges++;
> + cmem->max_nr_ranges = nr_ranges;
> + cmem->nr_ranges = 0;
>
> - /* If crashk_low_res is not 0, another range split possible */
> - if (crashk_low_res.end)
> - ced->max_nr_ranges++;
> + return cmem;
> }
>
> static int exclude_mem_range(struct crash_mem *mem,
> @@ -293,10 +278,8 @@ static int exclude_mem_range(struct crash_mem *mem,
> return 0;
>
> /* Split happened */
> - if (i == CRASH_MAX_RANGES - 1) {
> - pr_err("Too many crash ranges after split\n");
> + if (i == mem->max_nr_ranges - 1)
> return -ENOMEM;
> - }
>
> /* Location where new range should go */
> j = i + 1;
> @@ -314,11 +297,10 @@ static int exclude_mem_range(struct crash_mem *mem,
>
> /*
> * Look for any unwanted ranges between mstart, mend and remove them. This
> - * might lead to split and split ranges are put in ced->mem.ranges[] array
> + * might lead to split and split ranges are put in cmem->ranges[] array
> */
> -static int elf_header_exclude_ranges(struct crash_elf_data *ced)
> +static int elf_header_exclude_ranges(struct crash_mem *cmem)
> {
> - struct crash_mem *cmem = &ced->mem;
> int ret = 0;
>
> /* Exclude crashkernel region */
> @@ -337,8 +319,7 @@ static int elf_header_exclude_ranges(struct crash_elf_data *ced)
>
> static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
> {
> - struct crash_elf_data *ced = arg;
> - struct crash_mem *cmem = &ced->mem;
> + struct crash_mem *cmem = arg;
>
> cmem->ranges[cmem->nr_ranges].start = res->start;
> cmem->ranges[cmem->nr_ranges].end = res->end;
> @@ -347,7 +328,7 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
> return 0;
> }
>
> -static int prepare_elf64_headers(struct crash_elf_data *ced, int kernel_map,
> +static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,
> void **addr, unsigned long *sz)
> {
> Elf64_Ehdr *ehdr;
> @@ -356,12 +337,11 @@ static int prepare_elf64_headers(struct crash_elf_data *ced, int kernel_map,
> unsigned char *buf, *bufp;
> unsigned int cpu, i;
> unsigned long long notes_addr;
> - struct crash_mem *cmem = &ced->mem;
> unsigned long mstart, mend;
>
> /* extra phdr for vmcoreinfo elf note */
> nr_phdr = nr_cpus + 1;
> - nr_phdr += ced->max_nr_ranges;
> + nr_phdr += cmem->nr_ranges;
>
> /*
> * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
> @@ -455,29 +435,27 @@ static int prepare_elf64_headers(struct crash_elf_data *ced, int kernel_map,
> static int prepare_elf_headers(struct kimage *image, void **addr,
> unsigned long *sz)
> {
> - struct crash_elf_data *ced;
> + struct crash_mem *cmem;
> Elf64_Ehdr *ehdr;
> Elf64_Phdr *phdr;
> int ret, i;
>
> - ced = kzalloc(sizeof(*ced), GFP_KERNEL);
> - if (!ced)
> + cmem = fill_up_crash_elf_data();
> + if (!cmem)
> return -ENOMEM;
>
> - fill_up_crash_elf_data(ced, image);
> -
> - ret = walk_system_ram_res(0, -1, ced,
> + ret = walk_system_ram_res(0, -1, cmem,
> prepare_elf64_ram_headers_callback);
> if (ret)
> goto out;
>
> /* Exclude unwanted mem ranges */
> - ret = elf_header_exclude_ranges(ced);
> + ret = elf_header_exclude_ranges(cmem);
> if (ret)
> goto out;
>
> /* By default prepare 64bit headers */
> - ret = prepare_elf64_headers(ced,
> + ret = prepare_elf64_headers(cmem,
> (int)IS_ENABLED(CONFIG_X86_64), addr, sz);
> if (ret)
> goto out;
> @@ -496,7 +474,7 @@ static int prepare_elf_headers(struct kimage *image, void **addr,
> break;
> }
> out:
> - kfree(ced);
> + vfree(cmem);
> return ret;
> }
>
> --
> 2.16.2
>
Thanks
Dave
next prev parent reply other threads:[~2018-03-02 5:32 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-27 4:48 [PATCH 0/7] kexec_file: refactoring for other architecutres AKASHI Takahiro
2018-02-27 4:48 ` [PATCH 1/7] kexec_file: make an use of purgatory optional AKASHI Takahiro
2018-03-02 5:58 ` Dave Young
2018-03-02 6:11 ` Dave Young
2018-03-02 7:26 ` AKASHI Takahiro
2018-02-27 4:48 ` [PATCH 2/7] kexec_file,x86,powerpc: factor out kexec_file_ops functions AKASHI Takahiro
2018-03-02 5:04 ` Dave Young
2018-03-02 5:24 ` AKASHI Takahiro
2018-03-02 5:53 ` Dave Young
2018-03-02 6:08 ` Dave Young
2018-03-02 7:16 ` AKASHI Takahiro
2018-03-02 7:56 ` Dave Young
2018-02-27 4:48 ` [PATCH 3/7] x86: kexec_file: purge system-ram walking from prepare_elf64_headers() AKASHI Takahiro
2018-02-27 4:48 ` [PATCH 4/7] x86: kexec_file: remove X86_64 dependency " AKASHI Takahiro
2018-03-02 5:19 ` Dave Young
2018-03-02 5:33 ` AKASHI Takahiro
2018-02-27 4:48 ` [PATCH 5/7] x86: kexec_file: lift CRASH_MAX_RANGES limit on crash_mem buffer AKASHI Takahiro
2018-03-02 5:31 ` Dave Young [this message]
2018-03-02 5:36 ` AKASHI Takahiro
2018-02-27 4:48 ` [PATCH 6/7] x86: kexec_file: clean up prepare_elf64_headers() AKASHI Takahiro
2018-03-02 5:39 ` Dave Young
2018-03-02 5:58 ` AKASHI Takahiro
2018-03-02 6:04 ` Dave Young
2018-02-27 4:48 ` [PATCH 7/7] kexec_file, x86: move re-factored code to generic side AKASHI Takahiro
2018-03-02 5:56 ` [PATCH 0/7] kexec_file: refactoring for other architecutres Dave Young
2018-03-05 2:36 ` Dave Young
2018-03-06 10:28 ` AKASHI Takahiro
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